~ Life on the Green Side

Monthly Archives: October 2016

Here’s a little trip down memory lane. This goes back to a June 2006 trip to northern Mexico hunting plants, studying plants, and talking plants. Our little tribe can only be characterized as an eclectic band of like minded souls, hell bent to document a wide range of desert lilies (Agaves, Hesperaloes, Yuccas, Dasylirions, and Nolinas). We were a band of horticulturists who never met a plant we didn’t like. Our mission was simple: Take three vehicles, camping equipment, act like we knew what we were doing, do our best to stay out of trouble, and when needed, we could count on my Spanish to sidestep our way out of jail. That was our plan and for the most part, it worked.

Here’s the group of enthusiastic plantsmen that made the trip

Near Las Varas, Mexico, George Hull at the base of the slope that leads to Agave Potrerana

George was at Mountain State Nursery, Phoenix, Arizona in 2006 and he’s now retired in Portland, Oregon, enjoying the good life. George remains the ultimate plantsman, designer, teacher, plant-savvy fellow and I deemed him the senior citizen of our group, even though he’s the same age as me but he acts more senior than I do). George is blessed with a sense of humor best taken in small doses.

Brian Kemble with a close friend, Agave scabra. Since 1980, Brian has been the Horticulturist at the Ruth Bancroft Gardens, Walnut Creek, California. With a required BA in Philosophy, he has many years of experience in the wonderful world of desert succulents. Of the group, Brian was the quickest to reach the mountain top, first to find a sought-after plant, and incessantly passionate about the world of desert and dry mountain plants.

Rob Nixon, environmental assessment professional from California, and a snake, spider and desert plant enthusiast. Rob was eager to bring spiders and snakes he had caught into the camp for what he thought was a good show and tell opportunity. Most of the team thought it was a poor idea. Janet would walk away.

Sam Joel-Schafer with an Agave americana ssp. protoamericana. Sam was the youngest in our expedition, a biochemistry graduate and Spanish-proficient rebel without a cause, cheerfully struggling for a career in juggling, a hand stands in the middle of a highway guy, and at last account doing quite well as a professional gypsy in South America. Sam was probably the most complete and self-satisfied member of our troop.

Sean Hogan, owner of Cistus Nursery, Portland, Oregon, admiring a wonderfully old mound of Mammillaria. Sean is an author, lecturer, landscaper, a walking encyclopedia on anything that has something to do with an obscure plant, and an introducer of new plants and new ideas in the Pacific Northwest. While his mastery of puns was punishing, Sean did bring a needed touch of sensitivity, culture and civility to our group

Greg Starr, owner of Starr Nursery, Tuscon, Arizona, wondering how he got here and how to get down. Greg is a fine botanist, teacher, and nurseryman of immense reputation and insight. Greg wrote the description of Agave ovatifolia, the rare whale’s tongue Agave found by Lynn Lowrey growing between 3000′ and 7000′ elevation in Nuevo Leon, Mexico (Starr, 2004). Greg’s nursery is a small but intense backyard mail order nursery. With a desert lily focus, this is dangerous work and best attacked by using rolled up newspapers, welder’s gloves, and a whole lot of pain management.

Janet Creech, my adventure-friendly, cookie-making wife, wanted to go on the trip right from the start. While I was a bit skeptical, I finally relinquished provided she promises to always be cheerful, never complain no matter what. For the most part, that is exactly what happened. As the only lady in an otherwise unkempt and untidy group, she found the whole experience a great adventure but probably not worth repeating.

On a canyon road near Las Varas, Mexico

The focus of this trip was mainly Agaves and other desert lilies, with several members on an intense succulent hunt, with particular emphasis on Escheverias, Crassulas, and other euphorbs of importance. It’s no secret I like real plants – big trees, shrubs, woody vines – but I did find it inspiring to travel with folks obsessed by plants less than the size of a salad plate. Every now and then I would demand a tree fix. Connected by walkie talkies, our caravan would pull to a stop to let me scramble down to the river to marvel at thousand year old Montezuma cypresses – while the rest would hang out at the road waiting on my return grumbling about losing time. Some of the escheverias we sought involved hiking miles over rough terrain to find some rare Escheveria only appreciated by getting down on your hands and knees to take it all in.

First, let’s say any plantsman who visits the wild lands of Mexico can’t help but fall in love with the botany. Once wetter and drier, once connected to the botany of the SE USA, drier and hotter times have forced plants into an evolutionary torture test. If you like desert plants, there’s no place like Mexico. If you like Agaves, this is heaven.

We started our expedition at the border town of Douglas, Arizona, and headed south along the San Madre Oriental mountain range – scooting between desert and mountain flora as we made our way south to just north of Mexico city. The return trip took us north and west through some of the San Madre Occidental mountain range before crossing back into the USA at Nogales, Arizona. It’s remarkable how remote and beautiful so much of Mexico’s mountain land remains. While there’s a genuine conservation ethic brewing, it’s also sadly true that livestock and humans have placed amazing pressure on all but the most remote regions of the country.

While we found, photographed and documented over 20 Agave species during the 2006 trip, there was one species that made the trip worthwhile, Agave potrerana. We caught it in bloom on the first day of our trip – 29o 21.672N, 106o 28.825W, and 5218’ elevation – on the road to Las Varas. Along the bumpy road into a canyon, we found Agave parryi scattered here and there in the mountains. About four miles into the canyon, one of our tribe spotted the snake-like red yellow inflorescence peeking over a ledge. After a brisk climb and crawl up a slope too steep for any normal human being, the group basked in the glory of this strange plant in flower. Smiles and handshakes were in order, about 100 digital and film images were taken, and seed was found from plants nearby. It was a good start to the trip.

Images of Agave potrerana in bloom near Las Varas, Mexico, June 12, 2006

Agave potrerana is rarely encountered but can be found at elevations between 5,000 and 8,000 feet in northern Coahuila and Chihuahua, essentially finding a home in sunny spots in oak-pine-grassland habitats. This part of north-central Mexico gets temperatures well below freezing in winter and this Agave is quite cold-hardy in cultivation, enduring temperatures at least down to the low 20’s Fahrenheit without injury. While Tony Avent reports it has withstood temps in the lower teens, we haven’t found that to be the case. As far as we can determine, it’s only marginally hardy here in the Pineywoods of East Texas and I’ve lost it several times during the past thirty years.

A. potrerana is not often seen in cultivation in USA gardens and it’s rather hard to find in nurseries although it is occasionally listed in Plant Delights and other specialty nursery catalogs. The plants are typically found as a single, with green or blue-green leaves about 3 feet long. The densely-flowered inflorescence with red to orange to red flowers can only be described as a showstopper. The infloresence is unbranched and ranges from 12 feet to over 20 feet tall.

I’ve only been back to the wild lands of Mexico once since this 2006 trip and things have changed. Political turmoil, gangs, and a penchant to kidnap foreigners and hold them for ransom has put a bit of a damper on trips to the back country. Add to the fact that my SFA Gardens staff didn’t think if I was held for ransom they could raise much over $3000 to get me back. Yet, this is a special place with a magical and wonderful botany, the kindest people in the world, and there’s a vista around every turn of the road. If you don’t like agaves, you might find the spirits of them refreshing. One of our stops was to get some gasoline and some pulque. It escapes me why the two were being sold at the same tienda but after a nip or two of pulque, it all seemed to make sense.

Propagation: Mist propagation of cuttings taken in late spring, early summer.

Relatively rare in cultivation in the USA, and still rarer still to bloom, I was amazed to find our nine-year old 25’ Emmenopterys tree in full bloom on July 12, 2007. I first thought our new bragging rights would bring bands, parades, speeches and never-ending press coverage. I imagined my plant-possessed friends breaking out in heart palpitations. Of course, none of that happened. We did get some good local press and my horticultural friends and I emailed each other and, yes, there was some excitement, but nothing front page. The blooming of this rarely blooming tree certainly couldn’t hold a candle to the hoopla that surrounded the blooming of Jack, the corpse flower (Amorphophallus titanum) in our shade house in June, 2004.

We accessioned two Emmenopterys henryi plants in 1998, one a gift from the JC Raulston Arboretum in North Carolina (SFA 183-98) and the other plant (SFA 431-98) has no source in our records. At any rate, both were planted in 1999 in the newly founded Ruby M. Mize Azalea Garden, now one of the four gardens under the SFA Gardens umbrella. Our two trees have grown vigorously and are quite attractive in foliage. Our largest tree, the first to bloom, is now a full 25’ tall and perhaps 20’ wide at this writing (Nov 2009). While apparently quite healthy, the tree has not bloomed since the 2007 event. Clean, large opposite leaves feature attractive red petioles. Our two trees rest under a high canopy pine forest and enjoys a moist well drained soil. Both trees have grown vigorously and sport attractive ridged light-colored bark that is quite striking. White flowers are in panicles about 6” high and 8” wide with individual flowers a little less than an inch wide. The flowers are reminiscent of Pinckneya pubens.

A little history: Emmenoptyers henryi enjoys a wide distribution in south central China and old trees are reported to reach over 100’. E.H. Wilson, renowned plant explorer, first introduced seed into the USA at the Arnold about 1907, but no plants seemed to have survived that original introduction. The first flowering in the USA was recorded in July, 1994, in the garden of Dr. Allen Hirsh of Silver Spring, Maryland, a suburb of Washington, D.C. This plant came from a 1979 introduction of seed to the Arnold Arboretum from the Nanjing Botanical Garden. Woodlanders Nursery in Aiken, South Carolina, received extra plants and Dr. Hirsh purchased his plant in 1988. When the plant bloomed it was fifteen feet tall. I have seen the plant in bloom at Garvan Gardens in July, 2007, near Hot Springs, Arkansas. Bill McNamara of Quarry Hill Botanical Garden was the first to bloom the plant on the west coast with a plant only six years old. The seed for that tree came from Quarryhill’s expedition to eastern Sichuan in 1996.

While the literature reports the plant is slow to bloom, most of those reports come from “northern” gardens. Perhaps it’s the stifling heat of summers in Texas that steered our plant into a rare flower show.

The graceful Mahonia is native of Mexico, a member of the Berberidaceae family and it’s a stellar part shade performer in the Mast Arboretum. While it can take full sun once well established, it’s probably best in part shade. Our oldest plant is placed in the worst possible site imaginable: a hard-packed, beat-down east Texas red clay right on the very edge of a hot parking lot in full sun. I laid a thermometer there one time and the lower branches were resting right next to 140 degree asphalt. Plant remained cheerful. July is miserable in Nacogdoches and summers can be brutally dry. Not only that, the spot is out of reach of the nearest solid-set sprinkler head. When Texans say that the 100+ degree heat is killing us, we mean it. We planted a small one-gallon plant in 1988 as a companion to a strange “shrub oak” from Mexico and then mulched the area heavily with three to four inches of composted pine bark. While the oak is history, the Mahonia has slowly matured into a 4′ tall and 6′ wide specimen.

Old scanned in photo from a long ago expedition to Mexico with Lynn Lowrey and Alice Staub taking pics of a Mahonia gracilis clinging to a rocky face.

Given a modicum of horticulture, this evergreen plant has a lot to offer. In good morning sun, new growth is a glossy and lustrous lime-green. In shade, the plant sports darker foliage with that same glossy nature. Unlike most Mahonias, there are no prickly leaf edges or thorny branches to work around. The graceful Mahonia, is smooth and soft to the touch.

Mahonia gracilis on a mountain side east of Saltillo.

On one expedition in the 1980’s, one of the most striking plants I encountered in the San Madre Oriental mountain range, western side, and up on a dry slope was a graceful Mahonia gracilis in full bloom. In this shady moist canyon, foliage color was amazing – clean and blue – which set up the perfect contrast for a celebration of bright yellow flowers. In the SFA Mast Arboretum, the winter interest is terrific for plants receiving morning and noon sun, a mixture of reds, oranges, yellows and light green. Plants grown in part-shade tend to be taller and open and fall color less exciting. Full morning sun, mulch, and an occasional irrigation in the worst of droughts is the best recommendation. Late-winter flowers are bright yellow and held on slightly erect racemes emerging from near the terminal buds. We have failed to successfully root a cutting and because of the early-womter blooming nature of the plant, we’ve failed to make seed. However, the long graceful shoots lend themselves to layering in nearby mulch, and plant numbers can be produced modestly in that manner.

Mahonia gracilis in full sun at the Mast Arboretum.

Actually, there are many Mahonias that should be planted in Texas for part shade winter and early spring interest. When planted in mass, few plants make a stronger impression. Mahonia fortunei has been dependable, although the 1989 zero degree event killed a few plants and burned many. There are several hybrids worth seeking: MahoniaX media cultivars ‘Underway’, ‘Winter Sun”, and “Lionel Fortescue” have performed well for years. The hybrid betweenMahonia bealei and M. lomariifolia “Arthur Menzies” is a knockout. M. bealei is a commonly used shrub to 6′ with strong architectural interest. M. trifoliata, a native of Texas and Mexico with sweet edible fruit, has performed well in the dry garden and sports a blue cast to the foliage.

Mahonia trifoliata at SFA Gardens

Finally, a most interesting naturally occurring hybrid is M. trifoliata X M. swaysei which was given to us by Logan Calhoun many years ago, a plant that has survived for over a decade at the front of the Mast Arboretum in a sunny, very well drained spot along Wilson Drive. Small and shaped like a meatball, we have yet to get viable seed and my skill at cutting propagation has been poor.

Canbyi oak is a mid-sized semi-evergreen oak that can be found in the Texas nursery and landscape trade. A fine specimen was planted in 1986 at the front of the SFA Mast Arboretum along Wilson Drive. This particular tree came from acorns collected at Nuevo Leon, Mexico, and was referred to by Lynn Lowrey, famous Texas plantsman, as the “evergreen form”. In most winters, it is evergreen but single digit temperatures remove the foliage but we’re never noticed limb die back or bud damage. This particular tree has never received irrigation and it did well during the epic drought here at SFA Gardens in 2010 and 2011.

Canbyi oak has proven to be very drought and alkaline tolerant in Texas. Sometimes referred to as the chisos oak, slender oak, or graceful oak, the range includes Nuevo Leon and Tamaulipas in Mexico, and the Chisos Mountains in Texas. The species is encountered in rocky canyons and is rarely abundant. Growth habit is 4-15 m. (16-50 ft.) tall and long branches are somewhat drooping, thus the word graceful. The bark is distinctively fissured and attractive.

Shiny green leaves are 7.5-10 (2.9-3.9 in.) long and 2-3 cm. (.8-1.2 in.) wide and are lanceolate to narrowly elliptical with a pointed apex. Acorns are small, 1.5 cm. (.6 in.) long, somewhat narrow and without a significant peduncle. The cup is shallow and covers only 1/4 to 1/3 of the cup. The nomenclature of Q. canbyi is complicated and there are a number of synonyms. It has been described as a variety of Q. graciliformis in the south of its range, northern Mexico, but most authors consider Q. gracilformis as a form of Canbyi oak. It is also associated with Q. langtry, which is also thought to be a form of Q. canbyi found near Langtry, Texas. Most impressive is the extremely clean foliage.

Propagation is normally via acorns and SFA seedlings appear quite uniform in spite of the fact that other oak species are nearby. There are obvious hybrids in a seedling batch but they are easy to segregate. There is one paper involving cutting propagation that does indicate some promise for rooting superior clones (McGuigan et al. 1996). That work indicated that semi-hardwood and hardwood cuttings did not root; however, softwood cuttings did show promise and a linear decrease in rooting in response to IBA was observed with the greatest rooting occurring for the 1500 PPM K-IBA treatment. More research is needed to better determine timing and rooting hormone effects on percent rooting. The authors noted that the rooted cuttings should be left undisturbed after rooting as the roots are very brittle and easily damaged.